Another paper for the Copenhagen train. This is an estimate according to the abstract. Here’s the abstract and the supplemental information, of course the publicly funded paper is behind the AAAS paywall.
From UCLA News: Last time carbon dioxide levels were this high: 15 million years ago, scientists report
By Stuart Wolpert October 08, 2009 Category: Research
You would have to go back at least 15 million years to find carbon dioxide levels on Earth as high as they are today, a UCLA scientist and colleagues report Oct. 8 in the online edition of the journal Science.
“The last time carbon dioxide levels were apparently as high as they are today — and were sustained at those levels — global temperatures were 5 to 10 degrees Fahrenheit higher than they are today, the sea level was approximately 75 to 120 feet higher than today, there was no permanent sea ice cap in the Arctic and very little ice on Antarctica and Greenland,” said the paper’s lead author, Aradhna Tripati, a UCLA assistant professor in the department of Earth and space sciences and the department of atmospheric and oceanic sciences.
“Carbon dioxide is a potent greenhouse gas, and geological observations that we now have for the last 20 million years lend strong support to the idea that carbon dioxide is an important agent for driving climate change throughout Earth’s history,” she said.
By analyzing the chemistry of bubbles of ancient air trapped in Antarctic ice, scientists have been able to determine the composition of Earth’s atmosphere going back as far as 800,000 years, and they have developed a good understanding of how carbon dioxide levels have varied in the atmosphere since that time. But there has been little agreement before this study on how to reconstruct carbon dioxide levels prior to 800,000 years ago.
Tripati, before joining UCLA’s faculty, was part of a research team at England’s University of Cambridge that developed a new technique to assess carbon dioxide levels in the much more distant past — by studying the ratio of the chemical element boron to calcium in the shells of ancient single-celled marine algae. Tripati has now used this method to determine the amount of carbon dioxide in Earth’s atmosphere as far back as 20 million years ago.
Aradhna Tripati
“We are able, for the first time, to accurately reproduce the ice-core record for the last 800,000 years — the record of atmospheric C02 based on measurements of carbon dioxide in gas bubbles in ice,” Tripati said. “This suggests that the technique we are using is valid.
“We then applied this technique to study the history of carbon dioxide from 800,000 years ago to 20 million years ago,” she said. “We report evidence for a very close coupling between carbon dioxide levels and climate. When there is evidence for the growth of a large ice sheet on Antarctica or on Greenland or the growth of sea ice in the Arctic Ocean, we see evidence for a dramatic change in carbon dioxide levels over the last 20 million years.
“A slightly shocking finding,” Tripati said, “is that the only time in the last 20 million years that we find evidence for carbon dioxide levels similar to the modern level of 387 parts per million was 15 to 20 million years ago, when the planet was dramatically different.”
Levels of carbon dioxide have varied only between 180 and 300 parts per million over the last 800,000 years — until recent decades, said Tripati, who is also a member of UCLA’s Institute of Geophysics and Planetary Physics. It has been known that modern-day levels of carbon dioxide are unprecedented over the last 800,000 years, but the finding that modern levels have not been reached in the last 15 million years is new.
Prior to the Industrial Revolution of the late 19th and early 20th centuries, the carbon dioxide level was about 280 parts per million, Tripati said. That figure had changed very little over the previous 1,000 years. But since the Industrial Revolution, the carbon dioxide level has been rising and is likely to soar unless action is taken to reverse the trend, Tripati said.
“During the Middle Miocene (the time period approximately 14 to 20 million years ago), carbon dioxide levels were sustained at about 400 parts per million, which is about where we are today,” Tripati said. “Globally, temperatures were 5 to 10 degrees Fahrenheit warmer, a huge amount.”
Tripati’s new chemical technique has an average uncertainty rate of only 14 parts per million.
“We can now have confidence in making statements about how carbon dioxide has varied throughout history,” Tripati said.
In the last 20 million years, key features of the climate record include the sudden appearance of ice on Antarctica about 14 million years ago and a rise in sea level of approximately 75 to 120 feet.
“We have shown that this dramatic rise in sea level is associated with an increase in carbon dioxide levels of about 100 parts per million, a huge change,” Tripati said. “This record is the first evidence that carbon dioxide may be linked with environmental changes, such as changes in the terrestrial ecosystem, distribution of ice, sea level and monsoon intensity.”
Today, the Arctic Ocean is covered with frozen ice all year long, an ice cap that has been there for about 14 million years.
“Prior to that, there was no permanent sea ice cap in the Arctic,” Tripati said.
Some projections show carbon dioxide levels rising as high as 600 or even 900 parts per million in the next century if no action is taken to reduce carbon dioxide, Tripati said. Such levels may have been reached on Earth 50 million years ago or earlier, said Tripati, who is working to push her data back much farther than 20 million years and to study the last 20 million years in detail.
More than 50 million years ago, there were no ice sheets on Earth, and there were expanded deserts in the subtropics, Tripati noted. The planet was radically different.
Co-authors on the Science paper are Christopher Roberts, a Ph.D. student in the department of Earth sciences at the University of Cambridge, and Robert Eagle, a postdoctoral scholar in the division of geological and planetary sciences at the California Institute of Technology.
The research was funded by UCLA’s Division of Physical Sciences and the United Kingdom’s National Environmental Research Council.
Tripati’s research focuses on the development and application of chemical tools to study climate change throughout history. She studies the evolution of climate and seawater chemistry through time.
“I’m interested in understanding how the carbon cycle and climate have been coupled, and why they have been coupled, over a range of time-scales, from hundreds of years to tens of millions of years,” Tripati said.
In addition to being published on the Science Express website, the paper will be published in the print edition of Science at a later date.
UPDATE: Bill Illis add this graph in comments, which brings up the obvious correlation questions.
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It sure does look like more ice hockey, but this is for CO2 not temperature… where is the data for temperature in their study? Surely if they can measure CO2 for 20 million years with their ice cores they think they can measure temperature and correlate the two into some relationship? Or am I mistaken about that?
How long for this paper to become publicly available and if available, not behind a pay-wall?
Just curoius, but is splicing Mauna Loa data onto the end of ice core graph any different than splicing modern temperature data onto tree ring chronologies? Is that better science?
I weep for the future of science…
Of course if the analysis is valid the question is: Did higher CO2 cause higher temperatures or did higher temperatures cause higher CO2, or were they both caused by something else, or was it just coincidence? I suppose they could both cause each other in an uncontrollable feedback loop leading to the end of all life on Earth… but since I’m typing this 14 million years later, that’s unlikely…
My understanding is that warmer oceans “outgassing” CO2 is well accepted, right?
All I can see here is “correlation is cause”. Well, women wear short skirts when the sun is shining, but I don’t think women wearing short skirts causes the sun to rise in the morning.
This is the kind of fluffery that makes me wonder whether I should be laughing or crying.
The amount of sheer falsehood is staggering. The dishonest phrasing (ie. use of the word “suggests” in a sentence intended to be taken as factual) is beyond annoying. I can’t figure out whether the woman is stupid or naive… or both.
The razor-straight handle on the hockey stick is absolutely retarded. The continuation to the “projected” values is nothing short of laughable.
This is not Science. Not even remotely close. It’s nothing more than propaganda and fear mongering for political purposes. I sincerely hope that at some point, SOON, this sort of dishonesty is both criminalized AND prosecuted.
Another hockey stick.
Don’t these people realise that that The man on the Clapham omnibus (Joe. Q. Public) ridicules their claims. Don’t they actually get out into the real world, meet real people?
Methinks I see another hockey stick! I wonder if this one has already been peer reviewed?
“By analyzing the chemistry of bubbles of ancient air trapped in Antarctic ice, scientists have been able to determine the composition of Earth’s atmosphere going back as far as 800,000 years, and they have developed a good understanding of how carbon dioxide levels have varied in the atmosphere since that time. But there has been little agreement before this study on how to reconstruct carbon dioxide levels prior to 800,000 years ago.”
Also, isn’t it assuming a bit too much to say “Comparison of CO2 Levels in Earth’s History” when it’s a core sample taken from Antarctica, not from multiple places on the Earth? Is CO2 uniform across the atmosphere? As a gas one might think so but…
What is the error rate for such measurements over such a vast amount of time? What is the accuracy and what is the confidence level in the estimate?
How come this doesn’t jive with other studies of CO2 that I’ve seen? (At the moment I don’t recall the links to them.)
Maybe someone could compare this study with other studies of CO2 over the past 20 millions of years?
To the authors of the study: Where is the raw data? How come this important paper (assuming it’s important) isn’t available to the public as Open Science? Where is the raw non-manipulated data? How was the data adjusted, please show your work with a program that audits every tiny little adjustment and tweak that is made to the data, otherwise the work is suspect. Please show all the programs and steps involved in the preparation of this paper. Please show all your assumptions and provide a scientifically based justification and rationale for such assumptions and for your conclusions. Please provide all photos and video and film and audio recordings of your work in progress especially the videos documenting the proper or improper handling of the ice cores! What you don’t have documentary video to audit your ice core handling? If not why not? If so, please provide it. Please publish all of this forthwith for review by the public that funded your study. Thank you.
“We report evidence for a very close coupling between carbon dioxide levels and climate.”
No mention of the ever present lag of co2 changes behind temperature changes here I notice.
So what? For me as a geologist 15 mil years is not so long ago. I find it much more frightening that just recently / 10.000 years ago there was an Ice age.
Fantastic news:
Two periods of Earth History with the same CO2 levels but temperature very different and sea level very different. Conclusion: The level of CO2 does not determine either temperature or sea level.
Or perhaps there is something to worry about.
“During the Middle Miocene (the time period approximately 14 to 20 million years ago), carbon dioxide levels were sustained at about 400 parts per million, which is about where we are today”
“In the last 20 million years, key features of the climate record include the sudden appearance of ice on Antarctica about 14 million years ago and a rise in sea level of approximately 75 to 120 feet.”
So the last time we had this level of CO2 it kicked off the ‘sudden appearance’ of ice at the poles. How the formation of ice caused a rise in sea-level quite escapes me.
O. Weinzierl (10:40:25) :
So what? For me as a geologist 15 mil years is not so long ago. I find it much more frightening that just recently / 10.000 years ago there was an Ice age.
That Train to Copenhagen might just get derailed due to an avalanche.
-of data by empirical results…
So I guess this study validates the Piri Reis map was drawn 15 million years ago. Who’d a thunk it? 😉
“By analyzing the chemistry of bubbles of ancient air trapped in Antarctic ice, scientists have been able to determine the composition of Earth’s atmosphere going back as far as 800,000 years, and they have developed a good understanding of how carbon dioxide levels have varied in the atmosphere since that time. But there has been little agreement before this study on how to reconstruct carbon dioxide levels prior to 800,000 years ago.”
Translation: “There has been little agreement but this study is what we believe. There will still be little agreement”
It’s nothing more than one interpretation of the ice core samples used. This is just an opinion piece and should not be classed as science.
Looks like they are recycling plots now… just change the titles and there they go… Something Mann et. al. can be proud of.
Yes and it was 5-6C warmer 15 million years ago . . . so why is it not warming for the last decade? 300 million years ago the CO2 level was about the same as now but the temperature was 1C lower. 450 million years ago the temperature was lower than now but CO2 was 10 times higher. How did those things happen?
http://www.freerepublic.com/focus/f-news/1644060/posts
Why does no-one pay attention to the lag of CO2 behind temperature? The only reasonable explanation is that temperature controls CO2. There is no empirical evidence that “carbon dioxide is a potent greenhouse gas.” We exceeded the highest CO2 in the last million years by 1910. On a 100-year time scale, the greenhouse effect in the atmosphere should be instantaneous. It isn’t there.
I thought there was a concern over a CO2 “smearing” effect in old ice cores that would “peak clip” the high CO2 peaks by averaging them into a wider band of ice? Something about CO2 diffusing a ‘small’ distance over 15,000,000 years that turns out to be a “large” time…
On tv today.
Scientist have discovered that 50 million years ago Antarctica was a tropical zone due to high CO2 levels.
The scientist could learn from this astonishing and unexpected event and draw lessons for the near future.
CO2 for fact is aable to melt the entire ice cap!
I propose we take this information and the current posting, wrap it in a disposal bag and throw it in the bin.
When I see a hockey stick I smell a rat.
But maybe our fresh Nobel Laureate can do something with it.
The past 9 months his only accomplishment has been the acquirement of the Peace Nobel Prize.
Maybe he can use the momentum to make huge advances on the bills currently discussed on the Hill.
I am convinced he will find the alarming state of our planet 50 and 15 years ago a huge threat for the near future.
I think, if true, it only proofs one thing!
If these events were so dramatic and destructive, we would not be here.
And that also goes for the polar bears.
Can I have my peace now?
I believe her method is called the “Carbonite Clumped Isotope Thermometer”
From he University CV:
“The work that I’ve done with John Eiler at Caltech has demonstrated that the carbonate ‘clumped isotope’ thermometer offers unparalleled opportunities for addressing a range of questions in paleoclimatology and paleoceanography. This innovative method constrains carbonate growth temperatures based on the temperature-dependent “clumping” of 13C and 18O bonds within carbonate solids, independent of any solid-fluid equilibria.”
For her to construct a temp proxy using this method she must have statistical data that contains her statistical methodology, correlation co-efficients, error bars, etc… I would also like to know how she correlated temperatures from so long ago? Does her study suffer the same fate of the Birstlecone and Yamal tree rings( divergence problems?)? If this study is so important, the entire study should be in public archives.
Also, the results of her study run against what Dr Lindzen of MIT says about the behavior of CO2 doubling. Both cannot be right.
So, once upon a time CO2 was higher. There’s was lots of life then. Therefore, there’s nothing to worry about, right?
Shortened ‘codetech’:
“…fluffery…
…sheer falsehood…. The dishonest phrasing….woman is stupid or naive… or both.
…. absolutely retarded. …
… propaganda… fear mongering…. dishonesty…”
Humm – you don’t like what you read then? Then, to be taken seriously, please refute it with something more than such insult ridden invective.
The flaw is the wild leap from what they hope are facts – their estimates of CO2 millions of years ago – to lessons for the present. That leap is tendentious.
Mann & Briffa are both in the Penalty Box for Illegal Use of the Stick, so the coach has sent in Aradhna Tripati to kill off the penalties.